The geologic area from St. Petersburg to the Ural Mountains (an area now known as the East European Platform), flanked on the north by the Baltic and Berents Sea coastline, was first studied in detail in the early 19th century. The initial geological map of the region, made by Strangeways (1822), provided an important starting point although it contained innaccuracies. In the same period, the biologist Heinz Christian Pander (1830, 1856, 1857) made many important discoveries of Baltic marine fossils from the Silurian and Devonian periods.
Permian strata along the
Murchison had previously defined the Silurian period from fossiliferous strata in England and Wales, and then helped to identify the subsequent Devonian period (Murchison 1839). In the process, he was able to show that various fossils in the Devonian strata of Britain were equivalent to those recently described in Russia by Pander.
These included the lobe-finned fish Holoptychius nobilissimus, first defined by Louis Agassiz, now placed in the porolepiform order established by Swedish paleontologist Erik Jarvik. Although closer to lungfishes (Dipnoi) than to the direct ancestors of tetrapods, one genus of porolepiforms named Laccognathus, recently found in both Latvia and Ellesmere Island was apparently amphibious along rivers (see section on tetrapods for more details).
In 1840-1841 Murchison and
Verneuil and A. von Keyserling, and a Russian minerologist, Lieutenant
formations east of
Fig.1: Map of Permian and Mesozoic geologic formations west of the Ural Mountains.
One of the main Permian zones
encountered lay within the flat topography of
Permian stratigraphy of the Russian Platform
The Permian in Russia is subdivided into three stages: Ufimian, Kazanian, and Tatarian, which are further subdivided into horizons, tetrapod zones, and faunal assemblages (fig.2).
The type sections of the Upper Permian are located in the eastern part of the Russian (East European) Platform and the Fore-Urals Trough in Tatarstan and Bashkortostan. In terms of overall geology, the Russian platform is underlain by a crystalline basement composed of Archean and Proterozoic rocks which are located at depths of 1500 to 2000 m and more. This is overlain by a sedimentary sheath composed (successively) of Devonian, Carboniferous, Permian, Jurassic, Cretaceous, Neogene and Quaternary rocks (Silantiev et al. 2013).
Fig.2: Permian Stages and Horizons in East European Russia, and their corresponding tetrapod zones and faunal assemblages (after Sennikov and Golubev 2005) .
Ufimian stage of the Permian in RussiaThe Ufimian stage of the Permian is subdivided into two horizens, the Solikamskian and the Shemshian. The lowermost is named for the town of Solikamsk, located near Perm, in the trough along the Urals. Here the type section of this horizon contains Lower and Upper subformations.
The Lower Solikamskaya Subformation, 170-200 m thick, consists of deeply buried dark-grey clays and marl which have no outcrops, and must be studied in boreholes. It conformably overlies the Kungurian strata, and its start is marked by the appearance of the non-marine bivalves Palaeomutela and Concinella, both absent in the Lower Permian in this area. It also has a few thin interbeds with rare marine bivalves of the genera Schizodus, Netschajewia, and Permorphus (Silantiev et al. 2013).
Other distinctive traits of the Palaeomutala genus, such as a cross-lamellar structure in the middle of its three shell layers, help secure its identification, making it a reliable indicator of freshwater bays and riverine settings during the Permian (Silantiev 1998). Based on multi-level sampling in both outcrops and wells, there are currently a number of proposed species, each correlated with different freshwater environments, ranging from water with fast currents to calm waters, and with fish and tetrapod fossil occurrences (Silantiev 2014). Palaeomutala is also found in Late Permian strata in China.
Fig.3: The mussel-like Palaeomutala, commonly found in Permian fresh water environments in the Russian Block (after Silantiev 1998). Its distinctive hinge mechanism with numerous tooth-like elements is shown.
The clam-shaped bivalve Concinella (fig.4) is also commonly found in Permian strata representing freshwater sites. Its type locations are along the Pechora River in Timan-Pechora Province, and in the Kuznetsk basin (Pogorovich 1977).
The Upper Solikamskaya Subformation, 50-240 m in thickness, is exposed on the right bank of the Kama River near the village of Tyulkino, 25 km north of Solikamsk,.This subformation is composed of alternating clays, marl, and limestones with abundant non-marine fauna of ostracodes and bivalves (Palaeomutela, Sinomya, Redikorella, and Concinella), and also with the remains of insects, fishes, and plants (Silantiev 1996).
The western edge of the Upper Solikamskaya Subformation also outcrops along the valleys of the Vyatka and Sheshma Rivers. Here it is composed mainly of grey marl and dolomite, up to 10–15 m thick. Three of the four non-marine bivalves already noted (Palaeomutela, Redikorella, and Concinella) also occur here, although rarely.
Fig.4: Casts of the clam-like freshwater bivalve Concinella, whose fossils are found in numerous Ufimian deposits (after Silantiev 1998) .
The later, Sheshmian Horizon of the Ufimian Stage outcrops in the lower part of the banks of the Kama River (upstream of the mouth of the Vyatka River), and in the basin of the Shemsha River, from which it received its name. This horizon is largely composed of red-bed sandstones, which are usually recognized as alluvial formations. Fossils include rare fish remains, leaf imprints, pollen and spores, and numerous non-marine bivalves including Palaeomutela and Concinella, both continuing from the previous Solikamskian horizon; and ostracodes, the tiny shrimp-like crustaceans often used as relatively precise stratigraphic or horizon markers. The Sheshmian Horizon is also associated with the tetrapod Clamorosaurus nocturus, the type fauna for the Inta Faunal Assemblage (fig.2; cf. Sennikov and Golubev 2005).
Clamorosaurus (fig.5) was a small temnospondyl amphibian about 23 cm (9 inches) long, dated at 273-272 mya. It was a member of the Eryopidae family, named for the type genus Eryops, which was first discovered in the Early Permian red beds of northern Texas (Cope 1882). Besides its very wide, shield-shaped skull, Clamorosaurus has large external nares or nostrils; both features are common to all members of the Eryopidae family. Comparisons have often been made between Eryopidae fossils found from the Ufimian stage of the Permian in the Russian Block, and those in the North American Permian basins of Texas, Oklahoma, and New Mexico, where Eryopidae are well represented in the latest stages of the Early Permian.
Fig.5: Skull of Clamorosaurus seen from above, showing its wide profile and relatively large nostril openings, and the dermal scales which functioned as a protective surface on the skull..
The second stage of the Russian Permian, the Kazanian, begins with the lower Sokian horizon (named for the Sok River) which mainly outcrops in the eastern part of Tatarstan, along the Kama River, and in the basins of the Sheshma, Zai, Menzela, and Ik rivers (Gusev, Burov, Esaulova et al. 1993). The Sokian horizon represents a marine incursion which covered lower elevations. It is composed of three formations of calcareous clays, each 10-40 m thick, containing fossils of shallow marine organisms including bivalves, bryozoans, brachiopods, crinoids, ostracodes, and foraminifers (Silantiev et al. 2013).
The Upper Kazanian substage, widespread in Taterstan, is called the Povolzhian horizon. Its lowest strata, called the Prikazansky formation, 45-50 m thick, begins with a limestone bed with a typical Lower Kazanian marine fauna including brachiopods and crinoids.
This changes to terrestial conditions in the higher formations of the Upper Kazanian stage, where a transition zone of clayish-marly rocks contain mostly non-marine bivalves as well as terrestrial plant remains. Marine and lagoonal facies of the Upper Kazanian occur on the right bank of the Volga River, near the villages of Pechishchi, Naberezhye Morkvashi, and Krasnovidovo, while continental facies occur on the Kama River near the towns of Sheremetyevka and Sentyak.The Belebeevskaya Formation, some 60-100 m thick, is composed of reddish-brown siltstones and sandstones which contains a mixed fauna including the freshwater mollusc Palaeomutela umbonata, fish scales and teeth, fragments of reptile bones, imprints of leaves and trees, and plant pollen and spores (Silantiev et al. 2013).
Tatarian stage of the Permian
The third and highest stage of the Permian, the Tatarian stage, represents a terrestial setting which was crossed by numerous rivers. This widespread stage, up to 200-250 m in thickness, is mainly exposed in in the watersheds of rivers, almost always overlying the eroded surface of the Kazanian. The Tatarian is composed of red-bed (variegated) clays, siltstones, sandstones, marls, dolomites, and limestones. These contain only non-marine fossils including bivalves, plants, insects, and vertebrates. The type sections are located outside Tatarstan, on the Vyatka River between the mouth of the Cheptsa River and the mouth of the Kobra River.
Fig.6: Middle and Late Permian sites along three river drainages in western Russia, including 1) the North Dvina River; 2) the Volga River; and 3) the Ural River (after Golubev 2000a, fig.6.).
The Tatarian is subdivided into Lower, Middle, and Upper substages, corresponding with the Urzhuminian, Severodvinian, and Vyatkian horizons. These have extensive fossil deposits of terrestial flora and fauna, which will be explored in several site areas described below.
Today, about 170 years
after the initial exploration of Permian deposits in Russia by
Murchison et al. (1845),
dozens of large Tatarian sites haved been mapped and intensely
investigated along the
drainages of the North Dvina, Volga, and Ural Rivers (fig.6, boxes
vertebrate fossils found
west of the Urals have been grouped
into several faunal assemblages
(fig 2, and Golubev 2000a). The Middle-to-Late Tatarian phase, known as
the Severodvinian Horizon, is defined on the basis of faunal
assemblages from three highly productive sites
including Kotel'nich, Ilyinskoe (Semin Ovrag), and Sokolki,
together grouped as the Sokolki Assemblage.
This is followed chronologically
by the Vayazniki Assemblage,
representing the very end of the Tatarian up to the
Permian-Triassic extinction. Together these provide the
Russian equivalent of the Middle to Late Permian, Pristerognathus
Fig.7: Map of the location of the Kotel`nich Middle Permian deposits, showing geologic formations (after Benton et al. 2012)Fossils from this area were first recorded by Krotov (1894, 1912), who, in mapping the regional geology, found isolated bones at a locality called Kotel'nich-1. Little further work was done in the area until twenty years later, in 1933, when a young geologist from Kazan University, S. G. Kashtanov, discovered two complete pareiasaur skeletons on the river bank near the village of Vanyushonki, 18 km south of Kotel'nich. The following year, Kashtanov found two more pareiasaur skeletons at an exposure 2 km further upstream , which he sent to the Paleontological Institute (PIN) in Moscow (Kashtanov 1934).
An expedition led by A. P. Hartmann-Weinberg, which arrived from Moscow the next year (1935), found two incomplete skeletons and two skulls of pareiasaurs near the village of Volki. Comparing the initial findings at Kotel`nich with those known from Sokolki, Ephremov (1937, 1941) established two earlier complexes of dinocephalians, and a later pareiasaurian complex. The latter (equivalent to the current Sokolki faunal assemblage; see fig. 2) has been subdivided into three subassemblages, with the Kotel'nich fauna now established as the earliest by Ivakhnenko (1987, 1992), preceding the Ilyiskoe and Sokolki fauna (Golubev 2000; Benton et al. 2012).
Further work by the Moscow PIN was delayed until after World War II, when in 1948, a team led by B. P. V'yushkov found four pareiasaur skeletons near Boroviki village. The next year, while searching along a 12 km stretch of the Vyatka River from Port Kotel'nich to Boroviki, they discovered thirteen more pareiasaur skeletons, six of these complete (Efremov and V'yushkov 1955).
In the 1990s, work led by D. L. Sumin from Moscow PIN recovered a wide variety of tetrapod skeletons, including dicynodonts, dromasaurs, therocephalians, and gorgonopsians, as well as pareiasaurs, of which 40 skeletons were found the banks of the Vyatka, near the villages of Boroviki and Mukha.Excavations since 1992 at Port Kotel'nich have found numerous dicynodont skeletons, which there outnumber those of pareiasaurs. Along the southern portion of the banks of the Vyatka both pareisaurs and a unique climbing reptile named Suminia have been found. The Vyatka Palaeontological Museum was established in Kotel'nich in 1994, and has excavated and documented over 390 tetrapod skeletons.
The main reptiles from the Kotel`nich outcrops include Deltavjatia (fig.9), large plant-eating pareiasaurs whose fossils are often found in groups. Also found are Suminia, an anomodont with unusually long arms, which may have been one of the first arboreal tetrapods. Other members of the Kotel`nich faunal assemblage are the gorgonopsian Viatkogorgon; the small insectivore parareptile Emeroleter (fig.10); and small carnivorous theriodonts (Benton et al. 2012).
The nearby Port Kotel`nich locality also produced fossils of the dicynodont Australobarbarus, as well as two pareiasaurs. Another, somewhat later site in the immediate area, Sokol’ya Gora, has yielded the fish-eating chroniosuchian Chroniosaurus, the basal biomarsuchian Proburnetia, and the Pareiasaur Scutosaurus karpinski, the latter more commonly found in Late Permian deposits along the North Dvina river at Sokolki (Golubev 2000; Benton et al. 2012).
Fig.9: Skeleton of Deltavjayia vjatkensis, a Middle Permian pareiasaur from the Kotel`nich deposits (after photo by Khlyupin in Benton et al. 2012, fig.13).
Equally well represented at Kotel'nich are small, carnivorous
of the Nycteroleteridae family, of which the type genus,
I.A. Efremov in the 1930s for
their large eyes, suggesting night hunting, the
family also includes the genera Emeroleter
("day thief", named
in 1998 by
("large thief"), and Bashykroleter.
Their body size is about 20-25 cm, with a relatively large skull 5-7 cm
Many examples of Nycteroleter were found starting with the 1930s excavations by PIN. In recent excavations sponsored by the Vyatka Palaeontological Museum, two complete skeletons of the genus Emeroleter (fig.10), one adult and one juvenile, were found together in a fossil burrow (Khlyupin 2007).
The Upper Tatarian at Mutovino
The Late Tatarian stage of the East European Platform is formed mainly of rocks of lacustrine–alluvial origin The exposure on the Sukhona River around Mutovino was formed in the marginal part of the delta of a river that originated on the Baltic shield (Golubev 2013). The Sukhona River in this location makes a little northward curve between the villages of Purtovino and Isady. The northern or left bank contains a cliff 50m high and nearly 3 km long, composed of banded strata of gray and red Permian rocks. In the middle part of this outcrop, 2.5 km downstream from the mouth of the Mutovka River, and 1.2 km downstream from the Mutovino site, there is a large lens of clay and siltstone deposits, containing abundant remains, of plants, ostracodes, ,insects, bivalves, fish, and tetrapods. Fossil diversity is typically low in this zone, so that a site like Mutovino with a variety of significant terrestrial and aquatic taxa provides unusual opportunities for understanding the period (Golubev 2013).
The locality was formed in the marginal part of the delta of a river originating on the Baltic Shield and flowing into a large lake located in the northeastern part of the Moscow Syneclise.The Mutovino lens is located in the middle part of the riverbank slope. It is clearly visible from a distance, standing out against the bluish gray– red banded background of the enclosing deposits by its speckled, mostly dark gray coloration. The gray color is a prominent feature of this lens, distinguishing it from all other large Permian lenses of the Sukhona and Northern Dvina rivers, which usually have yellow– brown coloration.
At the level of its maximum thickness, the lens cuts into the underlying deposits to Bed 24; its base is located 9.6 m higher than the top of the limestone of Bed 3. The deposits overlying the lens begin with Bed 75 (lower beds are indistinguishable; they are either absent or facially changed); thus, the maximum thickness of the length is 20 m. The position of the edges of the lens could not be determined precisely; therefore, the length of the lens was estimated approximately as at least 200 m.
Fig.11: Map of Late Permian sites along the Northern Dvina and Sukhona Rivers in western Russia. Most sites have either of two subassemblanges of the Sokolki Fauna (Solkolki and Ilinskoe), while another site (Rasha) has the later Vayazniki Faunal Assemblage (after Golubev 2000a, fig.6).
The lens is complex in structure. It is formed mostly of fine texture matter: clay, siltstone (prevailing), and very fine to fine grained sandstone. All rocks are strongly carbonaceous and usually contain scattered fish and tetrapod bones and bivalve and ostracode shells. The upper part of the lens is formed of siltstones and clays gray, browngray, brown, horizontally laminated, containing fossil plant remains, bivalves, insects, ostracodes, and conchostracans.
The rocks of the Mutovino lens contain a diverse assortment of both plant and vertebrate fossils. Mutovino is one of the richest localities of Late Permian nonmarine organisms in European Russia. Fossils found here include abundant plant remains (15 forms), bivalves (six forms), insects (at least 102 forms), ostracodes (14 forms), conchostracans, fishes (at least seven forms), and tetrapods (five forms).
The most abundant plant fossils include shoots of the conifers Quadrocladus schweitzeri, in association with strobili of Dvinostrobus sagittalis. The subdominant fossils are leaves of the peltasperm pteridosperm Tatarina conspicua, in association with peltate ovuliphores of Peltaspermopsis, seeds of Salpingocarpus bicornutus, S. variabilis Meyen, and sporangia of Permotheca striatifera and P. vesicasporoides (Golubev 2013).
There are also abundant fossilized leaves of the cardiolepids Phylladoderma annulata , P. rastorguevii, and P. trichophora In addition, leaves of the Rhaphidopteris type have been found. Sporebearing plants are represented by leaves and megaspores of the lycapod Lepidophylloides delicata. Other fossil plants from this locality include leaves with venation of the Taeniopteris type, assigned to a new fern genus, Fefilopteris.
Abundant fish bones belong to Isadia sukhonensis A. Minich, (?) I. aristoviensis A. Minich, Isadia sp., Geryonichthys longus A. Minich, Geryonichthys sp., Mutovinia stella Minich, Strelnia certa A. Minich, Toyemia tverdochlebovi Minich, and Actinopterygii ordo indet. (Tatarskie otlozheniya …, 2001).
The tetrapod oryctocoenosis is represented exclusively by aquatic and subaquatic forms. The dominant fossils are the chroniosuchid anthracosaur Chroniosaurus levis Golubev (63%). Somewhat less abundant are the temnospondyl Dvinosaurus primus Amalitzky (26%). The kotlassiomorphs Microphon sp. and Microphon arcanus Bulanov occur less frequently (8%). The predatory therapsid Gorgonopidae gen. indet. (2%) and large phytophagous parareptile Pareiasauridae gen. indet. (1%) are represented by isolated specimens.The insect assemblage is particularly diverse. To date, the insects described and reported from this locality include members of 69 families, 81 genera, and 105 species, representing 25 orders.
Permian fossil assemblages on the
In 1892, about the same time as
the fossil beds of Kotel`nich were first investigated, the Russian
P. Amalitzky examined large
concretions found along
The Late Permian exposures
The Dvina River fossils were found to represent a rich variety of synapsids, reptiles, and amphibians, as well as freshwater mollusks, and plant fossils including Glossoptera. This Permian conifer is normally found only in southern latitudes of Gondwanaland, but its occurrence at various Late Permian sites on the Russian platform, such as those along the Dvina River, provide a well-known exception.
died in 1918,
could complete the publication of his reports on the Late Permian
They published an initial portion of the findings as “The North Dvinia excavations by Professor Amalitzky,” in two parts, one on Dvinisaurs and the second on Seymourians. A summary of the findings was also published in 1922 in the Bulletin of the Russian Academy of Sciences (Amalitsky 1922). Provoslavlev (1927) thereafter edited and published material from the Amalitzky findings on gorgonopsians, and Sushkin (1929) on Dvinia and Dicynodon.
the first exhibit
of fossil vertebrates from Kotlas was also
held at the
The pareisaurs of the Northern Dvinia region, represented by 13 skeletons, 30 craniums, and many other isolated bones, are somewhat smaller in body size than those in the Karoo basin in South Africa, such as Bradysaurus. The Russian pareiosaurs are otherwise notable for the widely varying sculptured bosses on their skulls, and for unique patterns of dermal scales or body armor on their exteriors.
A prominent example is Scutosaurus karpinski (fig.12), originally named Pareiosaurus karpinskii by Amalitzky (1922, pp. 334-335). This large animal, 2.45 m in length, had its back covered with star- shaped dermal plates, and its belly covered with small conical bosses. Three related species named by Amalitzky were Pareiosaurus elegans, P. tubercularum, and P. horridus, the latter nearly 3 meters in length, with horn-like projections on its cheeks and lower jaws. These three species were later combined into one, as Scutosaurus karpinskii (Ivakhnenko 2008).
Fig.12: Skull of Scutosaurus karpinskii seen from above and from the left side. The drawing shows intricate patterns of dermal scales serving as armor.
The theriodonts were represented by the large gorgonopsian Inostranzevia alexandri, of which two complete skeletons were found, their craniums 55 and 51 cm. long. These late gorgonopsians had extremely large, serrated canine teeth, as well as strong incisors, and conical molars, which were only in the upper jaw, the lower jaw lacking any molars (Amalitzky 1922, p.336).
the species Anna Petri
(named for Anna Amalitzky),
with two skulls lacking the lower
considered most similar to rhat of Scylacosaurus
Cynodonts found at Sokolki include the stem mammal Dvinia prima (fig.13), a small to medium-sized carnivore with large upper canines, whose skull length was 7-10 cm. Dvinia, initially studied by P.P. Sushkin, was more completely defined by Tatarinov (1968). Dvinia is considered close to several South African forms from the Late Permian and Early Triassic, including Trithelodontia (Broom), Gomphognathus, Trirachodon, and Diademodon.
Fig.13: Skull of Dvinia prima, with bones labelled.
Sushkin (1927) also noted features of the middle ear region of Permocynodon, a taxa closely related to Dvinia, which Tatarinov (1968, pp.3-6) later redefned as the same species. These otic features included a contact between the stapes and the paraoccipital process, and the presence of an opening called the foramen stapediale. Tatarinov placed Dvinia in the Procynosuchoid superfamily, and because of its distinct anatomy, Dvinia was placed within its own family, Dviniidae. Dvinia has advanced or transitional features of both the middle ear and a double set of both reptilian and mammalian jaw hinges (Tatarinov 1968, p.33).The skeletal material of Kotlassia prima, a primitive Seymourian amphibian from the Upper Permian of the
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